Rear Wiper/Washer

Circuit Operation

Rear Wiper/Washer System Components
The rear wiper/washer system consists of the following components:
- Rear wiper motor
- Rear washerpump
- Rear washrelay
- Rear wiper/washer switch
- LGM 30A fuse
- WASH 20Afuse

Rear Wiper/Washer System Controls
- Body control module
- Liftgate control module
- Rear wiper/washer switch

Rear Wiper/Washer System Operation
The rear window wiper/washer switch is an input to the body control module. The requested rear wiper mode is sent to the liftgate control module by the body control module as a message on the serial data circuit, and the rear window wiper motor is controlled by the liftgate control module. The switch power circuit to the rear wiper/washer switch is a 12-volt reference supplied by the body control module. The rearwiper/washer switch is a series of resistors and the switch position is determined by the voltage of the rear wiper/washer switch signal circuit to the body control module. The rear wi per/washer switch has continuity at all times and the body control module expects a rear wiper/washer switch signal voltage in all switch positions including OFF. The rear wiper motor is supplied battery positive voltage and ground. The liftgate control module controls rear wiper motor operation through the rear wiper motor control circuit. The rear wiper motor control circuit is supplied a battery positive reference voltage by the rear wiper motor module and is pulse width modulated to ground bythe liftgate control module. The duty cycle of the pulse width modulation determines the rear wiper motor operating mode. The lift glass and lift gate ajar switches are inputs to the liftgate control module and rear wiper motor operation will be disabled whenever an ajar condition exists. The rear window washer pump is controlled by the body control module through the rear washer relay. Battery positive voltage is supplied to the coil and switch sides of the rear washer relay. When the rear window wash request is active the body control module energizes the relay by grounding the relay coil through the rear washer relay control circuit. When the relay is energized battery positive voltage to the relay switch is supplied to the washer pump control circuit.